It is not uncommon to build a tire by forming a carcass and applying the various layers of vulcanizable material to form the side walls and tread thereof to the carcass and introducing the tire body thus produced into a tire press which is closed upon and defines a mold or form complementary to the configuration of the tire to be produced.
The heating medium is supplied to the form in the press and heats the vulcanizable rubber composition within the form from the exterior while a heating medium may be supplied to a bladder within the tire as well so that the combined heating effect will be sufficient to bring about vulcanization and the ultimate shaping of the tire.
In general, the vulcanization duration of tire bodies in presses having such vulcanization forms is controlled by timers which established fixed, although selected, heating periods.
During the operation of the press, however, fluctuations occur in the operating conditions and these include especially temperature variations of the heating fluid medium which is employed, usually superheated steam-heated water or hot gases, and these fluctuations are not considered or taken into account in normal operations.
When controls are provided to respond to such fluctuations, they are intended primarily to ensure the appropriate minimum heating necessary to avoid underheating or incomplete vulcanization and do not prevent overheating which may contribute to a reduction of the quality of the product or result in a waste of energy and an increase in cost.
It has been proposed to monitor the heating operation utilizing a temperature sensor which can be introduced into the tire blank or body, but because of mechanical disturbances, especially for closure of the press and the breaking out of the tire after vulcanization has been complete, can damage the sensor or interfere with an effective monitoring.